Japanese patent publication 59/115352 published Jul. 3, 1984 to Unitika discloses compositions of 100 parts by weight of a thermoplastic polyester, such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT); 1-50 parts by weight of an olefin/glycidyl(meth)acrylate copolymer, optionally also containing vinyl acetate; and 3-50 parts by weight of a polyolefin modified with up to 10 mole percent of an alicyclic carboxylic acid. The goal of the invention is a polyester-type resin composition with improved impact resistance. The composition of this publication is a thermoplastic engineering resin, while that of the present invention is a thermoplastic elastomer.
U.S. Pat. No. 4,172,859 granted Oct. 30, 1979 to Epstein, discloses a hard thermoplastic composition consisting of 60-99 weight percent thermoplastic polyester, toughened with a discrete soft elastomeric phase. Among the tougheners specifically disclosed are ethylene/vinyl acetate/glycidyl methacrylate (E/VA/GMA) and the zinc salt of E/iso-butyl acrylate (iBA)/methacrylic acid (MAA). Combinations of tougheners are permitted. This patent, however, does not disclose compositions with a minor proportion of polyester, nor recognize the need for sequential addition.
WO85/03718 published Aug. 29, 1985, discloses also a polyester rich (60-97%) composition, thus not a thermoplastic elastomer. The polyester is toughened with up to 40 weight percent of an ethylene copolymer such as E/n-butyl acrylate (nBA)/GMA. Less than 16% of an ionomer may be added as a nucleating agent. Again, no mention is made of sequential addition. The present invention is directed to soft flexible resins where the ionomer is the major component.
Japanese patent publication 57-187350 published Nov. 18, 1982 to Dainippon, discloses a blend of PET (100 parts by weight) with ionomer (0.1-15 parts by weight), aromatic polyester-polyether elastomer (0.5 to 25.0 parts by weight), and 0-10 parts by weight of polycarboxylic anhydrides, polyepoxides and/or polyisocyanates. The composition of the present invention has much less PET, and is a thermoplastic elastomer, rather than a toughened molding compound.
U.S. Pat. No. 4,284,540 granted Aug. 18, 1981 to Iida et al, discloses polyethylene terephthalate (PET) molding compositions which comprise PET resins, a copolymer of alpha-olefins and glycidyl ester and barium salt of fatty acids. This reference does not contain an acid copolymer or ionomer as does the present invention.
U.S. Pat. No. 4,555,546, granted Nov. 26, 1985 to Patel, discloses compatabilized polymer blends of olefin polymer, cross-linkable acrylic ester copolymer rubber, and a compatabilizing graft copolymer which is comprised of segments compatible with the olefin polymer and the copolymer rubber, respectively. However, nothing in Patel suggests the particular selection of ingredients which are used to make the compositions of the present invention, much less the particular quantitative limits specified for such ingredients, or the need for sequential addition of those ingredients.
U.S. Pat. No. 4,310,638, granted Jan. 12, 1982 to Coran et al, discloses thermoplastic elastomeric compositions comprising neutralized acrylic copolymer rubber modified with nylon. Coran discloses a simple two-component blend where one component comprises 60-98% neutralized acrylic rubber and the other component comprises 2-40% nylon. Coran does not recognize the significance of a third component which grafts the other two components together.
U.S. Pat. No. 4,694,042 granted Sep. 15, 1987 to McKee et al, discloses thermoplastic molding materials containing 5-50 parts by volume thermoplastic material as a coherent phase and 95-50 parts by volume of crosslinked emulsion polymerized elastomeric polymer. No mention is made of a GMA containing copolymer.
Japanese Patent Publication No. 59-086677 published May 18, 1984 to Sumitomo Chemical K.K., discloses blends of polyesters, glycidyl-containing ethylene copolymers and vinyl hydrocarbon polymers which have excellent adhesiveness, molding properties and workability. Those compositions, however, contain greater than 30% polyester and do not disclose an acid-containing ethylene copolymer. In addition, no mention is made of the importance of the order of addition of the components of the composition.
European Patent Publication No. 234819 published Sep. 2, 1987 to Sumitomo Chemical Company, Limited discloses binary blends of 5-59 parts polyamide and 95 to 41 parts of an acid-containing ethylene copolymer. No mention is made of a glycidyl-containing copolymer.
Great Britain Patent Publication No. 2,164,342, published Mar. 19, 1986 discloses a moldable composition comprising a blend of a resilient thermoplastic material and a potentially ionizable copolymer of ethylene and an alpha, beta-unsaturated carboxylic acid which is ionized. This reference does not contain a glycidyl-containing copolymer as does the present invention.